Drop on Demand Colloidal Suspension Inkjet Patterning for DIC
Drop on Demand Colloidal Suspension Inkjet Patterning for DIC
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DOI：
10.1007/s40799-018-0260-3
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发表时间：
2018-08
影响因子：
1.6
通讯作者：
S. Koumlis;S. Pagano;G. Retuerta del Rey;Y. Kim;P. Jewell;M. Noh;L. Lamberson
中科院分区：
文献类型：
--
作者：
S. Koumlis;S. Pagano;G. Retuerta del Rey;Y. Kim;P. Jewell;M. Noh;L. Lamberson
数字图像相关 (DIC) 是一种非接触式光学全场位移测量技术，用于通过跟踪表面特征来绘制施加负载下物体的变形。它是实验力学中广泛使用的方法，部分原因在于其易于设置以及跨长度尺度和材料系统的适用性。最常见的是，DIC 表面图案由喷漆或喷枪涂抹的对比鲜明的黑白斑点组成，这可能缺乏斑点尺寸分布的控制和一致性。在本文中，介绍了胶体悬浮液的按需滴注（DOD）喷墨打印，作为在微米到介观尺度上精确应用散斑图案的方法。将点阵列和伪随机 DOD 图案应用于高密度聚乙烯 (HDPE) 样本，按照 ASTM D695-15 进行压缩测试，并与传统喷枪散斑方法进行比较。结果表明，DOD 伪随机模式比其他两种方法提供了更一致的应变测量。阵列 DOD 和喷枪图案会引入错误信号，这可以根据两种不同的原理进行解释。众所周知，诸如阵列 DOD 之类的方向模式会在位移矢量识别中引入误差。对于随机喷枪图案，散斑尺寸的量化揭示了大部分散斑的特征长度尺度约为 1 像素，已知这会引入偏差误差，因为散斑图案的采样不满足奈奎斯特-香农采样定理。这些发现说明了 DOD 散斑对于某些 DIC 应用的实用性。
Digital image correlation (DIC) is a non-contact, optical, full-field displacement measurement technique used to map deformations on a body under an applied load by tracking surface features. It is a widely used method in experimental mechanics, owed in part to its ease of setup, and applicability across length scales and material systems. Most commonly, DIC surface patterns consist of contrasting black and white speckles applied by spray paint or an airbrush, which can lack control and consistency of the distribution of speckle sizes. In this paper, drop on demand (DOD) inkjet printing of colloidal suspensions is introduced as a means to apply a speckle pattern with precision on the micro- to mesoscale. A dot array and pseudo-random DOD pattern are applied to high-density polyethylene (HDPE) specimens, tested in compression following ASTM D695-15, and compared with a traditional airbrush speckle method. The results show that the DOD pseudo-random pattern provides a more consistent strain measurement than the other two methods. The array DOD and airbrush patterns introduce erroneous signals which can be explained on the basis of two different principles. A directional pattern, such as the array DOD, is known to introduce errors in the displacement vector identification. For the random airbrush pattern, a quantification of the speckle sizes revealed a large fraction of speckles that had a characteristic length scale of around 1 pixel, which is known to introduce bias errors, since the sampling of the speckle pattern does not satisfy the Nyquist-Shannon sampling theorem. These findings illustrate the utility of DOD speckling for certain DIC applications.